4 Answers
4

Sounds Firewall-y - check the firewall status on the target machine and try with it turned off (if it's on). If it is a firewall issue, you could leave it off OR modify the settings to allow connections on port 22. If you need help with this just holler.

Went to systems -> preferences -> firewall and uncheck/rechecked SSH and hit apply/reload. For some reason even though SSH was checked, the port had not been opened. After this, it works.
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jonderryMar 9 '11 at 22:03

Is your desktop ssh daemon listening on 192.168.100.XXX IP or only on lo interface?
Check in /etc/ssh/sshd_config file for line ListenAddress IP (or 0.0.0.0 to listen on all)
and be sure you have the line Port 22 in it too.

Looks like both laurent-rpnet and Linker3000 have a point in this.
Either the ssh is not listening on ethernet, or firewall is blosking requests, or both.
Check the listener with "netstat -ltn" and look for "0.0.0.0:22" for OK, or "127.0.0.1:22" for BAD.
Check the firewall by turning it temporally off by "service iptables stop", then try to ssh in, and remember to restart the firewall "service iptables start".